In this article I will explain with an example, how to use System.Text.Json JsonNamingpolicy to set CamelCase for JSON in ASP.Net Core (.Net Core 3).
Note: For beginners in ASP.Net Core (.Net Core 3), please refer my article ASP.Net Core 3: Hello World Tutorial with Sample Program example.
 
 

Configuring JSON Serializer setting to enable Camel Case

The first step is to configure the JSON Serializer settings in the Startup.cs file.
1. Open the Startup.cs class from the Solution Explorer window.
.Net Core 3: System.Text.Json JsonNamingPolicy set CamelCase
 
2. Inherit the following namespace.
using Newtonsoft.Json.Serialization;
 
3. Inside the ConfigureServices method of Startup.cs class, the AddJsonOptions method of the services object is called where the PropertyNamingPolicy is set JsonNamingPolicy.
This will remove the default Camel Case naming policy and JSON property names will remain intact as defined in the classes.
public void ConfigureServices(IServiceCollection services)
{
    services.AddControllersWithViews().SetCompatibilityVersion(CompatibilityVersion.Version_3_0)
            .AddJsonOptions(options =>
            {
                 options.JsonSerializerOptions.PropertyNamingPolicy = JsonNamingPolicy.CamelCase;
            });
}
 
Note: For working full sample, please refer my article .Net Core 3: Using jQuery AJAX in ASP.Net Core.